Bian Peiyu, Ye Chuantao, Zheng Xuyang, Luo Chuanyu, Yang Jiali, Li Mengyuan, Wang Yuan, Yang Jing, Zhou Yun, Zhang Fanglin, Lian Jianqi, Zhang Ying, Jia Zhansheng, Lei Yingfeng
Department of Infectious Diseases, Tangdu Hospital, Air Force Medical University, Xi'an, China.
Pathogenic Biology, Medical College of Yan'an University, Yan'an, China.
Front Microbiol. 2020 Mar 24;11:368. doi: 10.3389/fmicb.2020.00368. eCollection 2020.
Japanese encephalitis virus (JEV), the leading cause of viral encephalitis in Asia, is neurovirulent and neuroinvasive. Neurons are the main target of JEV infection and propagation. Receptor interacting serine/threonine-protein kinase 3 (RIPK3) has been reported to contribute to neuroinflammation and neuronal death in many central nervous system diseases. In this study, we found that the progression of JE was alleviated in RIPK3-knockout (RIPK3) mice in both peripheral and intracerebral infection. RIPK3-knockdown (RIPK3-RNAi) neuro2a cells showed higher cell viability during JEV infection. Moreover, the JEV load was significantly decreased in RIPK3 mouse-derived primary neurons and RIPK3-RNAi neuro2a cells compared with wild-type neurons, but this was not observed in microglia. Furthermore, RNA sequencing of brain tissues showed that the level of the interferon (IFN)-induced protein 44-like gene (IFI44L) was significantly increased in JEV-infected RIPK3 mouse brains, RIPK3 neurons, and RIPK3-RNAi-neuro2a cells. Then, it was demonstrated that the propagation of JEV was inhibited in IFI44L-overexpressing neuro2a cells and enhanced in IFI44L and RIPK3 double knockdown neuro2a cells. Taken together, our results showed that the increased expression of RIPK3 following JEV infection played complicated roles. On the one hand, RIPK3 participated in neuroinflammation and neuronal death during JEV infection. On the other hand, RIPK3 inhibited the expression of IFI44L to some extent, leading to the propagation of JEV in neurons, which might be a strategy for JEV to evade the cellular innate immune response.
日本脑炎病毒（JEV）是亚洲病毒性脑炎的主要病因，具有神经毒性和神经侵袭性。神经元是JEV感染和传播的主要靶标。据报道，受体相互作用丝氨酸/苏氨酸蛋白激酶3（RIPK3）在许多中枢神经系统疾病中导致神经炎症和神经元死亡。在本研究中，我们发现，在周围感染和脑内感染的情况下，RIPK3基因敲除（RIPK3 -/-）小鼠的日本脑炎病情均得到缓解。RIPK3基因敲低（RIPK3 -RNAi）的Neuro2a细胞在JEV感染期间显示出更高的细胞活力。此外，与野生型神经元相比，RIPK3基因敲除小鼠来源的原代神经元和RIPK3 -RNAi的Neuro2a细胞中的JEV载量显著降低，但在小胶质细胞中未观察到这种情况。此外，脑组织的RNA测序显示，在JEV感染的RIPK3基因敲除小鼠脑、RIPK3神经元和RIPK3 -RNAi的Neuro2a细胞中，干扰素（IFN）诱导蛋白44样基因（IFI44L）的水平显著升高。然后，证明了JEV在IFI44L过表达的Neuro2a细胞中传播受到抑制，而在IFI44L和RIPK3双基因敲低的Neuro2a细胞中传播增强。综上所述，我们的结果表明，JEV感染后RIPK3表达增加发挥了复杂的作用。一方面，RIPK3参与JEV感染期间的神经炎症和神经元死亡。另一方面，RIPK3在一定程度上抑制IFI44L的表达，导致JEV在神经元中传播，这可能是JEV逃避细胞固有免疫反应的一种策略。
